It is customary in commercial vehicles to use the internal combustion engine to assist the braking system and to reduce the brake system wear. Various systems are used to increase the braking performance of the internal combustion engine. It is known from the prior art to increase the braking performance via a corresponding valve lift curve. Here, for example, an additional cam can be activated or a completely new valve lift curve can be set by way of a switchover cam. Although an increased braking action can be achieved by way of the additional cam being switched in, the said braking action nevertheless cannot be set.